Isoindoles as Substrates

Most of the isoindole derivatives that have been used as substrates for phthalazine syntheses are in fact 1,3-isoindolinediones [phthalimides (244), 1,3-isoindolinediimines (245), or 3-hydroxy-1-isoindolinones (246)]. According to their substituents, these substrates may or may not require an ancillary synthon to furnish phthalazines. The use of each type of isoindoline derivative is discussed in an appropriate subsection that follows. 

These simple substrates react with hydrazines to give l,4(2//,3//)-phthalazine-diones, as illustrated in the following examples. 

3-Isoindolinedione (249) and t/jreo-2-hydrazino-l-methylpropanol gave threo-2-(2-hydroxy-1,2-dimethylethyl)-1,4(2f/,3f/)-phthalazinedione (250) (EtOH, 

18 h 22% after separation from unchanged substrate) the erythro- 

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